/*
 * Copyright (c) 1994, 1998, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package java.util;

/**
 * A class can implement the <code>Observer</code> interface when it
 * wants to be informed of changes in observable objects.
 *
 * @author Chris Warth
 * @see java.util.Observable
 * @since JDK1.0
 */
public interface Observer {

  /**
   * This method is called whenever the observed object is changed. An
   * application calls an <tt>Observable</tt> object's
   * <code>notifyObservers</code> method to have all the object's
   * observers notified of the change.
   *
   * @param o the observable object.
   * @param arg an argument passed to the <code>notifyObservers</code> method.
   */
  void update(Observable o, Object arg);
}
